JP4689408B2 - Bearing holding structure, developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a bearing for supporting rollers such as a developing roller, a transfer roller, and a conveying roller in a monochrome or color image forming apparatus that performs electrophotographic image formation such as a copying machine and a printer.

  As a conventional roller mounting method, there is a method of improving the accuracy of the axial position of the roller and the distance between the shafts of other rollers by providing a positioning member for positioning the roller (see, for example, Patent Documents 1 and 2). .

  As another roller mounting method, there is considered a method in which an opening is provided in a bearing holding portion for holding a roller bearing so that the number of parts is not increased and the assembling property is improved. (For example, see Patent Document 3).

  However, in such a roller mounting method, since the strength of the opening is weakened, there has been a problem in that the accuracy of the roller position is lowered by the deformation of the opening in the direction of opening the opening. .

Therefore, as a bearing of the developing device that solves such a problem, there is an apparatus that prevents the opening from being deformed in the direction of opening the opening by providing an expansion preventing means on the bearing that supports the developing carrier and the supply roller. It is known (see, for example, Patent Document 4).
JP-A-3-249780 JP-A-8-169588 Japanese Patent Laid-Open No. 10-20660 Japanese Patent Laid-Open No. 11-272072

  However, in conventional bearings, the strength of the bearing holding portion in the roller axial direction is weak, so the bearing holding portion falls in the roller axial direction, the accuracy of the roller position decreases, the housing and the bearing are damaged, the roller shaft and the bearing There has been a problem that an increase in the load on the device occurs.

  The present invention has been made to solve such a problem, and prevents the bearing holding portion from falling in the roller axis direction, thereby lowering the accuracy of the roller position, damaging the casing and the bearing, It is an object of the present invention to provide a bearing, a developing device, a process cartridge, and an image forming apparatus that can prevent an increase in load on the bearing.

The bearing holding structure of the present invention is connected to the bearing that supports the shaft of the roller, the hole-shaped opening in which the bearing is mounted, the outer peripheral rib formed on the outer periphery of the hole-shaped opening, and the hole-shaped opening. a bearing holding structure consisting of the bearing holder of substantially C-shaped, said shaft for holding said bearing and an opening passing through during assembly of the roller, the bearing, the hole-shaped opening The fitting portion to be fitted and the opening portion is deformed in a direction to open the opening by pressing the outer peripheral rib of the bearing holding portion when the fitting portion is rotated around the fitting portion and set to the bearing holding portion. A rib-shaped opening preventing portion that prevents the fitting, and one end side of the fitting portion in the axial direction of the roller, in a state in which the fitting portion is rotated around the fitting portion and set in the bearing holding portion. In the bearing holder A substantially disc-shaped collar portion that contacts one end side in the axial direction of the roller, and provided on the other end side in the axial direction of the roller in the fitting portion, and rotates around the fitting portion to hold the bearing. When the bearing holding portion is set to a portion, the bearing holding portion comes into contact with the other end side of the roller in the axial direction of the roller and sandwiches the bearing holding portion in the axial direction of the roller together with the collar portion, thereby A tilt-preventing portion that prevents the shaft from falling in the axial direction, and the bearing holding portion includes a rotation-stopping portion that stops rotation of the bearing when the opening-preventing portion abuts against the center of the developing roller and the center An angle formed by a straight line passing through the point where the opening preventing portion hits the rotation stop portion and a straight line passing through the opening center of the opening and the center of the developing roller is 60 ° or more and less than 180 ° It has a certain configuration.

With this configuration, the bearing holding portion is sandwiched between the collar portion and the fall prevention portion in the roller axial direction, so that the bearing holding portion is strong in the roller axial direction, and the bearing holding portion is prevented from falling in the roller axial direction. Therefore, it is possible to prevent a decrease in accuracy of the roller position, breakage of the housing or the bearing, increase in load on the roller shaft or the bearing, and the like. In addition, by pinching the bearing holding part from the roller axial direction, the bearing holding part is prevented from falling in the roller axial direction, so that the accuracy of the roller position is reduced, the housing and the bearing are damaged, the roller shaft and the bearing Can be prevented from occurring. Further, since the rotational force applied to the bearing by the rotation of the roller is prevented from acting in the direction of opening the opening of the opening and the positional accuracy of the roller is prevented from being lowered, a high-quality device can be realized.

Moreover, the bearing structure of this invention has the structure which the said fitting part and the said hole-shaped opening part fit by a clearance fit .

With this configuration, no force is applied in the opening direction of the opening .

  Further, the bearing of the present invention has a snap fit portion for attaching to the bearing holding portion, and the snap fit portion is configured to be snap fit by rotating the bearing in a circumferential direction of the roller. Have.

  With this configuration, since the bearing is held by a snap fit by rotation, the mounting can be facilitated.

  The bearing of the present invention has a configuration in which the rotation direction of the roller in the circumferential direction is the same as the rotation direction when the main function of the roller is activated.

  With this configuration, since the snap-fit portion is not subjected to a load due to the rotation of the roller, the bearing can be made difficult to come off from the bearing holding portion.

  Moreover, the bearing of this invention has the movement prevention part which prevents the peripheral components slid and attached to the axial direction of the said roller from moving to an axial direction.

  With this configuration, since the bearing also serves to prevent other components from falling off, the number of components can be reduced.

  The developing device of the present invention has a developing roller whose shaft is supported by the bearing.

  This configuration makes it easy to assemble the developing roller of the developing device, which is a unit that is manufactured and recycled a lot, and makes it easy to remove only the developing roller, which is a consumable item during recycling. Can be realized. In addition, a high-quality developing device can be realized in order to prevent a decrease in the positional accuracy of the roller.

  The process cartridge of the present invention has a configuration in which the developing device is incorporated.

  This configuration makes it easy to assemble the developing roller of the developing device, which is a unit that is manufactured and recycled many times, and makes it easy to remove only the developing roller, which is a consumable item during recycling. Can be realized. In addition, a high-quality process cartridge can be realized in order to prevent a decrease in the positional accuracy of the roller.

  The image forming apparatus of the present invention has a configuration in which the developing device is incorporated.

  With this configuration, it is possible to realize an image forming apparatus with low running cost and high reliability by using a high-productivity and high-quality developing device.

  The image forming apparatus of the present invention has a configuration in which the process cartridge is incorporated.

  With this configuration, an image forming apparatus with low running cost and high reliability can be realized by using a process cartridge with high productivity and high quality.

  The image forming apparatus of the present invention further includes a transfer roller on which the bearing is supported.

  With this configuration, the position accuracy of the transfer roller is improved, and the assembling property and the recyclability are increased. Therefore, a high-quality and high-productivity image forming apparatus can be realized.

  In addition, the image forming apparatus of the present invention includes a transfer roller for a transfer medium on which the bearing is supported.

  With this configuration, since the positional accuracy of the transfer roller of the transfer object is improved, and the assembling property and the recyclability are improved, it is possible to realize a high quality and high productivity image forming apparatus.

  In the developing device of the present invention, the bearing holding portion has openings at both ends.

  With this configuration, in order to prevent the opening from being deformed in the direction in which the opening is opened and to prevent the roller from falling in the axial direction, the positional accuracy of the roller can be maintained even when the bearing holding unit has the opening on the developing device side. Since it does not decrease, it is possible to realize a developing device with even higher attachment properties.

  In the process cartridge of the present invention, the bearing holding portion has openings at both ends.

  With this configuration, in order to prevent the opening from being deformed in the direction in which the opening is opened and to prevent the roller from falling in the axial direction, the positional accuracy of the roller can be maintained even when the bearing holding unit has the opening on the developing device side. Since it does not decrease, a process cartridge with higher mountability can be realized.

  In the image forming apparatus of the present invention, the bearing holding portion has openings at both ends.

  With this configuration, in order to prevent the opening from being deformed in the direction in which the opening is opened and to prevent the roller from falling in the axial direction, the positional accuracy of the roller can be maintained even when the bearing holding unit has the opening on the developing device side. Since it does not decrease, it is possible to realize an image forming apparatus with even higher mountability.

  As described above, the present invention prevents the bearing holding portion from falling in the direction of the roller axis, and causes a decrease in the accuracy of the roller position, damage to the housing or the bearing, an increase in the load on the roller shaft or the bearing, and the like. The present invention provides a bearing, a developing device, a process cartridge, and an image forming apparatus that have the effect of preventing the above-described problems.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. In the present embodiment, an example in which the image forming apparatus is applied to a digital copying machine is illustrated.

  As shown in FIG. 1, a contact glass 2 and a slit glass 3 having a smaller area than the contact glass 2 are provided on the upper surface of the main body 1 a of the digital copying machine 1. In addition, an automatic document feeder (hereinafter also referred to as “ADF”) 4 is provided via a hinge mechanism (not shown) above the main body 1a of the digital copying machine 1 (here, on the contact glass 2 and the slit glass 3). The ADF 4 is openable and closable with respect to the contact glass 2 and the slit glass 3. The ADF 4 separates the originals taken out from the original bundle made up of a plurality of sheet-like originals placed on an original tray (not shown) one by one, conveys them to the reading position on the contact glass 2, and reads the original after reading. Is discharged to the discharge tray 5.

  On the other hand, below the contact glass 2 of the main body 1a, a scanner 6 having an exposure lamp, a mirror, a lens, an image sensor composed of a charge coupled device (CCD), etc. (not shown) is provided. The scanner 6 is driven by a driving device (not shown). In FIG. 1, it is configured to move in the left-right direction. The drive device scans the scanner 6 in the left-right direction when reading image information of a document that has been conveyed to a reading position on the contact glass 2 and stopped being conveyed under the control of a main body control unit (not shown). When reading the image information of the original while conveying the original from the glass 3 onto the contact glass 2, the scanner 6 is configured to stop below the reading position.

  Further, the image information of the original read by the scanner 6 is output as image data to the main body control unit, and the main body control unit writes the input image data and the photosensitive drum constituting the image forming unit 8 by the optical system 7. 9, an electrostatic latent image is formed, and a toner image is formed on the photosensitive drum 9 by the charging unit 10, the exposing unit 11, and the developing unit 12 constituting the image forming unit 8.

  On the other hand, under the control of the main body control unit, the transfer paper fed from the transfer paper feeding system 13 is conveyed to the image forming unit 8 in accordance with the image forming operation, and is transferred by the transfer unit 14 constituting the image forming unit 8. The toner image is transferred to the first surface of the paper, and further, the toner image is fixed by the fixing system 15 and then conveyed to the transfer reversal discharge unit 16.

  Here, the path A in the transfer reversal discharge unit 16 is a path for immediately discharging the transfer paper out of the digital copying machine 1, and the path B reverses the transfer paper in the transfer reversal discharge unit 16. This is a path for discharging paper out of the apparatus. Further, in the path C, the transfer sheet is reversed in the transfer reversal discharge unit 16 and the transfer sheet is fed again on the double-sided tray. This is a path for discharging the transfer sheet to the outside of the apparatus via path A after being transferred and fixed.

  Next, the developing unit 12 will be described. FIG. 2 is a simplified diagram of the developing unit according to the embodiment of the present invention.

  As shown in FIG. 2, the developer is stored in the developing device casing 17 or a separate developer storage section, and this developer is supplied to the supply roller bearing held in the developing device casing 17. 22 and a supply roller bearing (not shown) are conveyed to a supply roller 21 rotatably received at both ends. Here, as a means for conveying the developer to the supply roller 21, in addition to supplying the developer to the supply roller 21 by its own weight, the developer can be supplied while loosening the developer using an agitator, a paddle or the like. The developer conveyed to the supply roller 21 is conveyed to the developing roller 18 that is rotatably received at both ends by the developing roller bearings 19 and 20 held in the developing device casing 17 in the same manner as the supply roller 21.

  The developer conveyed to the developing roller 18 is held on the surface of the developing roller 18, and passes through the developing blade 24 of an elastic member supported by the holder 23 and brought into contact with the developing roller 18 with a constant pressure. Is regulated. At the same time, the developer is positively (negatively) charged by frictional charging or charge injection, so that a thin layer of the developer is uniformly formed.

  On the other hand, an electrostatic latent image is formed between a high potential portion and a low potential portion drawn on a photosensitive member (not shown) that is arranged with contact or a minute gap by regulating the distance between the axes using a contact roller or the like. It is formed. Then, the thinned developer moves onto the photoconductor according to the formed electrostatic latent image to form a toner image. At this time, the developer that has not moved onto the photoreceptor is neutralized by a neutralizing unit (not shown), and returns to the developer storage unit provided in the developing device casing 17 or separately.

  The toner image formed on the photosensitive member moves to the document through a necessary number of transfer means and is fixed on the document by the fixing system 15. Then, the document is discharged from the paper discharge port and can be obtained as a printed image.

  Next, assembly of one end of the developing roller 18 will be described. FIG. 3 is an explanatory view illustrating assembly of one end of the developing roller according to the embodiment of the present invention.

  As shown in FIG. 3, the developing roller bearing holding portion 25 is opened in a substantially C shape, and the developing roller shaft 18a is assembled into the opening 25a from a direction perpendicular to the developing roller axis. Next, the developing roller 18 is positioned at a predetermined position by inserting the developing roller bearing 19 from the outside in the developing roller axial direction by passing the fall preventing portion 19f having a narrower width than the opening 25a between the openings 25a. The

  Next, the shape of the developing roller bearing 19 will be described. FIG. 4 is a view showing a developing roller bearing according to the embodiment of the present invention.

  As shown in FIGS. 3 and 4, the developing roller bearing 19 has a fitting portion 19 d for fitting with the opening 25 b of the developing roller bearing holding portion 25. Here, the type of fitting includes intermediate fitting or gap fitting, and gap fitting is particularly preferable from the viewpoint that no force is applied in the opening direction of the opening 25a.

  Further, the developing roller bearing 19 is rotated after the fitting portion 19d is fitted into the opening portion 25b, and the outer peripheral ribs 25d and 25e of the developing roller bearing holding portion 25 which are substantially C-shaped (shown in FIG. 5). ) Are respectively provided to prevent opening 19a and 19b. Here, the opening prevention parts 19a and 19b are arranged at positions substantially opposed to each other. Further, as the type of fitting, intermediate fitting is preferable from the viewpoint of fitting the fitting between the opening preventing portions 19a and 19b and the outer peripheral ribs 25d and 25e.

  Further, the developing roller bearing 19 includes a fall preventing portion 19f arranged so as to sandwich the developing roller bearing holding portion 25 together with the collar portion 19c in order to prevent the developing roller bearing holding portion 25 from falling in the axial direction of the developing roller. Have.

  Next, assembly by rotation of the bearing will be described. FIG. 5 is a cross-sectional view of a state in which the developing roller bearing according to the embodiment of the present invention is pushed into the developing roller shaft from the axial direction.

  The developing roller bearing 19 is inserted into the developing roller bearing holding portion 25 from the outside in the developing roller axial direction in order to hold the developing roller shaft 18a. At this time, the fall preventing portion 19f passes through the opening 25a and the opening preventing portion. 19a and 19b enter the outer sides of the outer peripheral ribs 25d and 25e. Next, as shown in FIG. 5, by rotating the developing roller bearing 19, the opening preventing portions 19a and 19b are moved to positions where the opening 25a is suppressed. At this time, the fall-preventing portion 19f also rotates about the developing roller shaft 18a, and a part of the opening 25a is sandwiched together with the collar portion 19c. Even if the load increases, position accuracy can be prevented from being lowered.

  The developing roller bearing holding portion 25 has a rotation preventing portion 25c for preventing the developing roller bearing 19 from rotating during operation. Normally, the developing roller bearing 19 is similarly provided with a rotation preventing portion. However, in this embodiment, the opening prevention part 19b is abutted against the rotation stop part 25c. This is due to space restrictions. However, if there is enough space, it is preferable to provide the anti-rotation part separately from the opening prevention part 19b in order to prevent concentration of one point of load.

  Further, the developing roller bearing holding portion 25 may be provided with a minute protrusion that protrudes so as to contact the rotation stopper 25c near the base of the opening prevention portion 19b. Thereby, the force applied to the developing roller bearing holding portion 25 can be reduced.

  Further, the developing roller bearing 19 is provided with a snap fit portion 19e that acts in the rotation direction. The snap fit portion 19e is snap fitted to the locking portion 25f by rotating the developing roller bearing 19 in the rotation direction of the developing roller 18. As a result, the developing roller bearing 19 is not detached after the mounting, so that the assemblability is improved, and it is not necessary to use a thrust direction stop such as an E-ring. Further, since the developing roller bearing 19 also serves to prevent the supply roller bearing 22 from coming off, it is possible to further reduce the thrust direction stopping parts such as the E-ring.

  Next, the position of the rotation stopper 25c will be described. 6 and 7 are cross-sectional views showing a state in which the developing roller bearing according to the embodiment of the present invention is pushed into the developing roller shaft from the axial direction. 6 and 7, the straight line drawn from the center of the opening to the center of the developing roller 18 is taken as the x axis, and the straight line passing through the center of the developing roller shaft 18a and perpendicular to the x axis is taken as the y axis.

  First, the case where the rotation stopper 25c is provided in the second quadrant will be described with reference to FIG. In this case, when the developing roller 18 rotates, the developing roller bearing 19 also generates a rotational force in the rotational direction. When the rotation stopping portion 25c receives this rotational force in the second quadrant, it acts in the direction of pushing down the second quadrant portion of the developing roller bearing holding portion 25. Further, the reaction force generated when the opening preventing portion 19b hits the rotation preventing portion 25c acts to push up the first quadrant portion of the developing roller bearing holding portion 25 by the fitting portion 19d. Since the direction of this action is the direction of closing the opening, it is possible to prevent the position accuracy of the developing roller shaft 18a from being lowered. Thereby, it can be said that the rotation stopper 25c only needs to be arranged in the second quadrant.

  Next, the case where the rotation stopper 25c is provided in the fourth quadrant will be described with reference to FIG. In this case, when the developing roller 18 rotates, the developing roller bearing 19 also generates a rotational force in the rotational direction. When the rotation stopping portion 25c receives this rotational force in the fourth quadrant, it acts in the direction of pushing up the fourth quadrant portion of the developing roller bearing holding portion 25. Further, the reaction force generated when the opening preventing portion 19b hits the rotation preventing portion 25c acts in a direction in which the third quadrant portion of the developing roller bearing holding portion 25 is pushed down by the fitting portion 19d. Since the direction of this action is to open the opening, not only the position of the developing roller shaft 18a is shifted, but also the developer may leak from between the developing roller 18 and the developing device casing 17.

  Here, when the rotation stopper 25c is provided between the first quadrant and the fourth quadrant, the relationship between the angle α of the position of the rotation stopper 25c and the moment exerted by the force opening direction component is as shown in FIG. become. Thus, if 60 ° ≦ α ≦ 90 ° in the first quadrant, it can be said that the magnitude of the force acting in the direction of opening the opening is small and the variation thereof is small, which is suitable for the arrangement.

  Further, when the anti-rotation portion 25c is provided in the third quadrant, since the force exerted by the anti-rotation portion 25c and the force exerted by the reaction force both act in the direction of opening the opening, the arrangement in the third quadrant should be avoided. is there.

  As described above, the rotation stopper 25c is preferably arranged at a position of 60 ° ≦ α ≦ 180 ° (there is actually 180 ° because there is the opening 25a). Considering stress, the angle α is most preferably around 100 °. In addition, when it must be arranged in the third quadrant or the fourth quadrant due to space restrictions or the like, it is preferable to set the angle α at 270 ° because the force in the opening direction becomes small.

  In the present embodiment, the bearing of the developing roller has been described. However, the same effect can be obtained even when the bearing of the present invention is applied to a roller mounted on the image forming apparatus such as a paper feed roller or a conveyance roller.

  In addition, there are two types of paper feeding rollers and conveying rollers that rotate in accordance with their functions. In this case, it is preferable to provide a snap-fit portion on the roller bearing so as to be snap-fitted by rotating in a rotational direction having a high frequency among these rotational directions.

1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention, and is a schematic configuration diagram of a digital copying machine as an image forming apparatus. FIG. 2 is a simplified diagram of a developing unit according to an embodiment of the present invention. It is explanatory drawing explaining the assembly | attachment of the end of the developing roller which concerns on embodiment of this invention. It is a figure which shows the developing roller bearing which concerns on embodiment of this invention. It is sectional drawing of the state which pushed the developing roller bearing which concerns on embodiment of this invention into the developing roller axis | shaft from the axial direction. It is sectional drawing of the state which pushed the developing roller bearing which concerns on embodiment of this invention into the developing roller axis | shaft from the axial direction. It is sectional drawing of the state which pushed the developing roller bearing which concerns on embodiment of this invention into the developing roller axis | shaft from the axial direction. It is a figure which shows the relationship between the angle of the position of the rotation stopper which concerns on embodiment of this invention, and the moment which the opening direction component of an effect | action acts.

Explanation of symbols

1 Digital copier (image forming device)
12 Development unit (developing device)
18 Developing roller 18a Developing roller shaft 19 Developing roller bearing 19a Opening prevention part 19b Opening prevention part 19c Collar part (falling prevention part, movement prevention part)
19d fitting portion 19e snap fit portion 19f falling prevention portion 25 developing roller bearing holding portion 25a opening portion 25b opening portion 25c rotation stopping portion 25d outer peripheral rib 25e outer peripheral rib 25f locking portion

Claims (14)

A bearing that supports the roller shaft ;
And an opening in which the shaft passes with lead and the hole-shaped opening in which the bearing is mounted and the hole-shaped opening portion outer peripheral rib formed on the outer periphery of said hole-shaped opening during assembly of the roller A substantially C-shaped bearing holding portion for holding the bearing , and a bearing holding structure comprising :
The bearing is
A fitting portion fitted into the hole-shaped opening;
A rib-shaped opening that prevents the opening from being deformed in the direction of opening the opening by pressing the outer peripheral rib of the bearing holding portion when the fitting portion is rotated around the fitting portion and set in the bearing holding portion. A prevention unit;
One end side of the roller in the axial direction of the roller in the bearing holding portion provided at one end side in the axial direction of the roller in the fitting portion, and rotated around the fitting portion and set in the bearing holding portion A substantially disc-shaped brim that abuts against
The other end of the roller in the axial direction of the roller in the fitting portion, and the other end of the roller in the axial direction of the roller in the bearing holding portion when rotated about the fitting portion and set in the bearing holding portion A fall prevention portion for preventing the bearing holding portion from falling in the axial direction of the roller by sandwiching the bearing holding portion together with the flange in the axial direction of the roller ,
The bearing holding portion is
A rotation stop portion that stops rotation of the bearing when the opening prevention portion abuts, a straight line passing through a center of the developing roller and a point where the opening prevention portion abuts the rotation prevention portion, and an opening center of the opening portion bearing holding structure characterized in that the angle between the straight line passing through the center of the developing roller is less than 60 ° or 180 ° with. The bearing holding structure according to claim 1, wherein the fitting portion and the hole-like opening portion are fitted with a clearance fit . The bearing has a snap-fit portion for attaching to the bearing holding portion;
The bearing holding structure according to claim 1, wherein the snap-fit portion is snap-fitted by rotating the bearing in a circumferential direction of the roller. The bearing holding structure according to claim 3, wherein the direction of rotation of the roller in the circumferential direction is the same as the direction of rotation when the main function of the roller is activated. The bearing according to any one of claims 1 to 4, further comprising a movement preventing portion that prevents peripheral components attached by sliding in the axial direction of the roller from moving in the axial direction. Retaining structure .   A developing device comprising a developing roller having a shaft supported by the bearing according to claim 1. A process cartridge incorporating the developing device according to claim 6 . Image forming apparatus characterized by incorporating the developing device according to claim 6. An image forming apparatus incorporating the process cartridge according to claim 7 . An image forming apparatus comprising: a transfer roller whose shaft is supported by the bearing according to claim 1 . 6. An image forming apparatus comprising a transfer roller for a transfer medium, the shaft of which is supported by the bearing according to claim 1. The developing device according to claim 6, wherein the bearing holding portion has openings at both ends . The process cartridge according to claim 7, wherein the bearing holding portion has openings at both ends. The image forming apparatus according to claim 8, wherein the bearing holding portion has openings at both ends.

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